The processing of chip-size electronic components for placement on a printed circuit board is disclosed in commonly assigned U.S. patent application Ser. No. 299,979, filed Sept. 8, 1981. The disclosed system utilizes an air conveyor to transport chips, one at a time, from their respective input stations to a placement head that places them onto a printed circuit board. The disclosed system furthermore makes reference to sensing the size of the chip and thereafter adjusting the position of the chip relative to the placement head. The disclosed system does not however address how the size of a chip is sensed and differentiated from another chip size. The disclosed system moreover does not specifically address how a particular size of chip is caused to be centered underneath the placement head.